The present invention generally relates to a method and apparatus for obtaining information concerning the surface characteristics of a specimen and describes more particularly such method and apparatus as applied to measuring carbon black dispersion in rubber. The dispersion of carbon black in rubber or other elastomeric material is an indication of the quality, such as uniformity and mechanical properties, of rubber and other elastomeric materials. The level of dispersion, the spacial arrangement of the carbon black agglomerates per unit volume, and the size of each agglomerate are important factors considered in evaluating such quality. In one prior technique for measuring surface roughness of rubber as an indication of carbon black dispersion therein, the resistance to flow of air between the tested surface and a plane test surface resting thereon was measured using a Rugosimeter. In another prior technique, carbon black dispersion was measured using the Ameda System which includes a microscope, a photosensor, a scan drive apparatus to move various portions of a specimen into view of the microscope and photosensor, and substantial complex electronic circuitry for evaluating the photosensor response as it "viewed" the specimen. In the former technique the results obtained from any measurement represents an average value and lacks a certain degree of accuracy; and in the latter technique the time require to effect the necessary sample preparation, sample viewing, and signal analysis is extremely lengthy and the equipment for effecting the same extremely expensive.
In the past a diamond stylus has been used to detect the microstructure of a sample. In the present invention, however, it is the macrostructure, not the microstructure, that is to be sensed and converted to useful information representing carbon black dispersion in a specimen. Accordingly, in the present invention a rolling contact is made with the specimen to facilitate scanning of the specimen and gathering of information concerning the surface characteristics thereof.